Publication Abstracts
Sinclair et al. 2023
Sinclair, J.A., R. West, , C. Tao, G.S. Orton, T.K. Greathouse, R.S. Giles, D. Grodent, and L.N. Fletcher, 2023: Long-term variability of Jupiter's mid-infrared auroral CH4 emissions. Icarus, 46, 115740, doi:10.1016/j.icarus.2023.115740.
We present a study of the long term variability of Jupiter's mid-infrared CH4 auroral emissions. 7.7-7.9 µm images of Jupiter recorded by NASA's Infrared Telescope Facility, Subaru and Gemini-South over the last three decades were collated and analyzed in order to quantify the magnitude and timescales over which the northern auroral hotspot varies. We find that the ratio of the radiance of the poleward northern auroral emissions with a lower-latitude zonal-mean, henceforth 'Relative Poleward Radiance' or RPR, exhibits varability over a 37% range and apparently over a range of timescales. We searched for patterns of variability in order to test whether seasonally varying solar insolation, the 11-year solar cycle, or short-term solar wind variability at Jupiter's magnetopause could explain the observed evolution. The variability of the RPR exhibits a weak (r = 0.17) correlation with both the instantaneous and phase-lagged solar insolation received at Jupiter's high-northern latitudes. This rules out the hypothesis suggested in previous work (e.g. Sinclair et al. 2017a, 2018) that shortwave solar heating of aurorally produced haze particles is the dominant auroral-related heating mechanism in the lower stratosphere. We also find the variability exhibits negligible (r < 0.03) correlation with both the instantaneous and phase-lagged monthly-mean sunspot number, which therefore rules out a long-term variability associated with the solar cycle. On shorter timescales, we find moderate correlations of the RPR with solar wind conditions at Jupiter in the preceding days before images were recorded. For example, we find correlations of r = 0.45 and r = 0.51 of the RPR with the mean and standard deviation solar wind dynamical pressure in the preceding 7 days. The moderate correlation suggests that either: 1) only a subset of solar wind compressions lead to brighter, poleward CH4 emissions and/or 2) a subset of 8-µm brightening events are driven by internal magnetospheric processes (e.g. Io activity) and independent of solar wind enhancements.
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BibTeX Citation
@article{si01500z,
author={Sinclair, J. A. and West, R. and Barbara, J. M. and Tao, C. and Orton, G. S. and Greathouse, T. K. and Giles, R. S. and Grodent, D. and Fletcher, L. N.},
title={Long-term variability of Jupiter's mid-infrared auroral CH4 emissions},
year={2023},
journal={Icarus},
volume={46},
pages={115740},
doi={10.1016/j.icarus.2023.115740},
}
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RIS Citation
TY - JOUR ID - si01500z AU - Sinclair, J. A. AU - West, R. AU - Barbara, J. M. AU - Tao, C. AU - Orton, G. S. AU - Greathouse, T. K. AU - Giles, R. S. AU - Grodent, D. AU - Fletcher, L. N. PY - 2023 TI - Long-term variability of Jupiter's mid-infrared auroral CH4 emissions JA - Icarus JO - Icarus VL - 46 SP - 115740 DO - 10.1016/j.icarus.2023.115740 ER -
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